nRF9151 asset tracker dies in 15–93 days vs expected ~1 year — need help isolating field-vs-lab power gap

[Akshay]

Dear Nordic Team,

We are seeking assistance in resolving a significant power consumption gap observed in our nRF9151-based asset tracker. While our lab testing suggests a battery life of approximately one year, units in the field are failing much earlier.

Setup

- Hardware: nRF9151, mfw 2.0.4, 2× EVE ER34615 in parallel (38 Ah Li-SOCl₂). Note: Two pilot units include a supercap; one does not.

- Network: T-Mobile USA, LTE-M Band 12, PSM enabled (T3324=20s, T3412=60 min granted), eDRX disabled, Onomondo APN.

- Workload: GNSS uplink every 5 minutes and shadow-delta poll every 30 minutes.

- Firmware: UART and modem traces disabled for production, IPv4-only PDN.

Observations

- Lab: Average current of 4–5 mA, with an expected battery life of 1 year. sleep current is less than 40uA.

- Field (with supercap): Battery life lasted approximately 93 days across two units.

- Field (without supercap): Battery life lasted approximately 15 days on one unit, which also experienced intermittent failures.

Questions

1. Do you have any guidance on how to identify whether this discrepancy originates from the modem side or specific network behavior?

2. What is the recommended debugging approach for this issue? Should we focus our efforts on modem traces, network signaling analysis, or both?

We would appreciate any insights you can provide to help us isolate this field-vs-lab power gap.

Best regards,

Akshay

[MidhunSqt]

Currently we only have access to DK which is located in Whiteplain NY ,US .Devices are in different location .  We can take modem traces of that only. Signaling log doesn't explicitly show anything about PSM as far as i know.

[Øyvind]

It will be difficult to tell from the devices that are out in the field, but if you are able to replicate issues with a DK then we can see what is going on in the modem. Our developers point out that GNSS fixes in the field might take longer than in lab. Do you have any logs to compare GNSS fix time in lab vs in field?

PSM enabled (T3324=20s, T3412=60 min granted),

They also point out that the active time is quite long, is there a reason for having such a long time? 

MidhunSqt said:

The battery is supported with supercap to mitigate such Burst pulse handling, that is how we designed it

Do you have any current consumption measurements when the device is active?